1. Field of the Invention
The present invention relates to a test indicator displaying a swing amount of a gauge head as a rotation amount of an indicating needle.
2. Description of Related Art
Among test indicators that display a swing amount of a gauge head as a rotation amount of an indicating needle, one is known to have a configuration in which a movement is unitized (see a conventional example illustrated in FIGS. 6-8 of Japanese Patent Laid-Open Publication No. H06-109401). This test indicator includes a body case; a gauge head swingably supported by the body case; a dial unit mounted on the body case; and a movement housed in the body case and magnifying a swing motion of the gauge head to transmit the magnified swing motion to the dial unit. A gauge head insertion opening to which the gauge head is inserted and an axis bearing that swingably supports an axis of the gauge head are formed at a foremost end of the body case, and a recess that houses the movement is formed inside the body case.
The gauge head is swingably supported at a middle part thereof by the body case, and has a contacting ball on a foremost end side beyond the supporting point and a first arm on a base end side. The dial unit is configured as one unit to include a unit body, an indicating needle rotatably provided in the unit body, a scale plate provided in the unit body along a rotation area of the indicating needle, and a pinion mounted on an axis of the indicating needle. The movement includes a pair of holding plates, a crown gear rotatably held between the pair of the holding plates and having a coaxial pinion, and a second arm rotatably held between the pair of the holding plates and having a sector gear at a foremost end side engaging the pinion of the crown gear. The second arm has a supporting axis on a base end side rotatably supported in the body case, and has a pair of transmission pins upwardly implanted thereon, one on each side of the supporting axis, the pair of the transmission pins being brought into contact with the first arm from mutually opposite sides.
Upon assembling, the dial unit and the movement unit are each assembled in advance. First, the movement is housed inside the body case and fixed in the body case with screws and the like. Thereafter, the gauge head is inserted from the gauge head insertion opening and the axis thereof is supported between a pair of axis bearings. In this case, the foremost end of the first arm is inserted from between the pair of holding plates of the movement in a manner not to interfere with the supporting axis and the transmission pins. Next, the recess of the body case is covered with a cover or the like. Finally, the dial unit is mounted on a long lateral face of the body case. In this case, the pinion of the dial unit is brought to engage the crown gear.
In the structure of the conventional test indicator, the movement is formed in advance having gears, the second arm and the like installed between the two holding plates. Therefore, after the movement is installed in the recess of the body case, it is necessary to install the gauge head having the first arm to the body case. However, the first arm has a complex shape, and the foremost end of first arm has to be inserted from between the two holding plates of the movement in a manner not to interfere with the supporting axis and the transmission pins. Therefore, the installation process requires high proficiency as well as time and effort. Further, in the structure of the conventional test indicator, the gauge head is supported by the body frame, and the gears and the second arm are supported by the two holding plates of the movement. Therefore, inter-axis precision is difficult to ensure, so that high precision requires a lot of adjustment time and labor, resulting in cost increase.